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Versions: (draft-boucadair-radext-tcpm-converter) 00

Network Working Group                                       M. Boucadair
Internet-Draft                                              C. Jacquenet
Intended status: Standards Track                                  Orange
Expires: April 9, 2020                                   October 7, 2019


               RADIUS Extensions for 0-RTT TCP Converters
                draft-boucadair-opsawg-tcpm-converter-00

Abstract

   Because of the lack of important TCP extensions, e.g., Multipath TCP
   support at the server side, some service providers now consider a
   network-assisted model that relies upon the activation of a dedicated
   function called Transport Converters.  For example, network-assisted
   Multipath TCP deployment models are designed to facilitate the
   adoption of Multipath TCP for the establishment of multi-path
   communications without making any assumption about the support of
   Multipath TCP by the remote servers.  Transport Converters located in
   the network are responsible for establishing multi-path
   communications on behalf of endpoints, thereby taking advantage of
   Multipath TCP capabilities to achieve different goals that include
   (but are not limited to) optimization of resource usage (e.g.,
   bandwidth aggregation), of resiliency (e.g., primary/backup
   communication paths), and traffic offload management.

   This document specifies a new Remote Authentication Dial-In User
   Service (RADIUS) attributes that carry the IP addresses that will be
   returned to authorized users to reach one or multiple Converters.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 9, 2020.





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Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  CONVERT RADIUS Attributes . . . . . . . . . . . . . . . . . .   4
     3.1.  CONVERT-IPv4  . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  CONVERT-IPv6  . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Sample Use Case . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  Table of Attributes . . . . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   One of the promising deployment scenarios for Multipath TCP (MPTCP,
   [RFC6824]) is to enable a host or a Customer Premises Equipment (CPE)
   connected to multiple networks (e.g., DSL, LTE, WLAN) to optimize the
   usage of such resources.  A deployment scenario relies on MPTCP
   Conversion Points (called, Transport Converters
   [I-D.ietf-tcpm-converters]).  A Converter terminates the extended TCP
   (e.g., MPTCP, TCPinc) sessions established from a host, before
   redirecting traffic into a legacy TCP session.  Further Network-
   Assisted MPTCP deployment and operational considerations are
   discussed in [I-D.nam-mptcp-deployment-considerations].

   Figure 1 shows a deployment example of the Converters to assist
   establishing MPTCP connections.




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  +------------+        _--------_    +----------------+
  |            |       (    LTE   )   |                |
  |   Host     +=======+          +===+  Backbone      |
  |            |       (_        _)   |   Network      |
  |            |         (_______)    |+--------------+|
  |            |       IP Network #1  ||   Converter  ||------> Internet
  |            |                      ||              ||
  |            |                      |+--------------+|
  |            |       IP Network #2  |                |
  |            |        _--------_    |                |
  |            |       (    DSL    )  |                |
  |            +=======+           +==+                |
  |            |       (_        _)   |                |
  +------------+        (_______)     +----------------+


                 Figure 1: "Network-Assisted" MPTCP Design

   [I-D.ietf-tcpm-converters] specifies the Converter as a function that
   is installed by a network operator to aid the deployment of TCP
   extensions and to provide the benefits of such extensions to clients.
   A Transport Converter supports one or more TCP extensions.

   Within this document, a Converter refers to a function that
   terminates a transport flow and relays all data received over it over
   another transport flow.  This element is located upstream in the
   network.  One or multiple Converters can be deployed in the network
   side.  The Converter achieves the following:

   o  Listen for client sessions;

   o  Receive from a client the address of the final target server;

   o  Setup a session to the final server;

   o  Relay control messages and data between the client and the server;

   o  Perform access controls according to local policies.

   The Converter element is located in the network.  One or multiple
   Converters can be deployed.

   This document specifies two new Remote Authentication Dial-In User
   Service (RADIUS, [RFC2865]) attributes that carry the Converter IP
   address list (Section 3).  In order to accommodate both IPv4 and IPv6
   deployment contexts, and given the constraints in Section 3.4 of
   [RFC6158], two attributes are specified.  Note that one or multiple




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   IPv4 and/or IPv6 addresses may be returned to a requesting CPE.  A
   sample use case is described in Section 4.

   This document assumes that the Converter(s) reachability information
   can be stored in Authentication, Authorization, and Accounting (AAA)
   servers while the CPE configuration is usually provided by means of
   DHCP ([RFC2131][RFC8415]).  Further Network-Assisted MPTCP deployment
   and operational considerations are discussed in
   [I-D.nam-mptcp-deployment-considerations].

   This specification assumes a Converter is reachable through one or
   multiple IP addresses.  As such, a list of IP addresses can be
   communicated via RADIUS.  Also, it assumes the various network
   attachments provided to an MPTCP-enabled host are managed by the same
   administrative entity.

   This document adheres to [RFC8044] for defining the new attributes.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119][RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  CONVERT RADIUS Attributes

3.1.  CONVERT-IPv4

   Description

      The RADIUS CONVERT-IPv4 attribute contains the IPv4 address of a
      Converter that is assigned to a host.

      Because multiple Converters IP addresses may be provisioned to an
      authorised host (that is a host entitled to solicit the resources
      of a Converter), multiple instances of the CONVERT-IPv4 attribute
      MAY be included; each instance of the attribute carries a distinct
      IP address.

      Both CONVERT-IPv4 and CONVERT-IPv6 attributes MAY be present in a
      RADIUS message.

      The CONVERT-IPv4 Attribute MAY appear in a RADIUS Access-Accept
      packet.  It MAY also appear in a RADIUS Access-Request packet as a
      hint to the RADIUS server to indicate a preference, although the
      server is not required to honor such a hint.



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      The CONVERT-IPv4 Attribute MAY appear in a CoA-Request packet.

      The CONVERT-IPv4 Attribute MAY appear in a RADIUS Accounting-
      Request packet.

      The CONVERT-IPv4 Attribute MUST NOT appear in any other RADIUS
      packet.

   Type

      TBA1 (see Section 7).

   Length

      6

   Data Type

      The attribute CONVERT-IPv4 is of type ip4addr (Section 3.3 of
      [RFC8044]).

   Value

      This field includes an IPv4 address (32 bits) of the Converter.

      The CONVERT-IPv4 attribute MUST NOT include multicast and host
      loopback addresses [RFC6890].  Anycast addresses are allowed to be
      included in a CONVERT-IPv4 attribute.

3.2.  CONVERT-IPv6

   Description

      The RADIUS CONVERT-IPv6 attribute contains the IPv6 address of a
      Converter that is assigned to a host.

      Because multiple Converter IP addresses may be provisioned to an
      authorised CPE (that is a host entitled to solicit the resources
      of a Converter), multiple instances of the CONVERT-IPv6 attribute
      MAY be included; each instance of the attribute carries a distinct
      IP address.

      Both CONVERT-IPv4 and CONVERT-IPv6 attributes MAY be present in a
      RADIUS message.

      The CONVERT-IPv6 Attribute MAY appear in a RADIUS Access-Accept
      packet.  It MAY also appear in a RADIUS Access-Request packet as a




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      hint to the RADIUS server to indicate a preference, although the
      server is not required to honor such a hint.

      The CONVERT-IPv6 Attribute MAY appear in a CoA-Request packet.

      The CONVERT-IPv6 Attribute MAY appear in a RADIUS Accounting-
      Request packet.

      The CONVERT-IPv6 Attribute MUST NOT appear in any other RADIUS
      packet.

   Type

      TBA2 (see Section 7).

   Length

      18

   Data Type

      The attribute CONVERT-IPv6 is of type ip6addr (Section 3.9 of
      [RFC8044]).

   Value

      This field includes an IPv6 address (128 bits) of the Converter.

      The CONVERT-IPv6 attribute MUST NOT include multicast and host
      loopback addresses [RFC6890].  Anycast addresses are allowed to be
      included in an CONVERT-IPv6 attribute.

4.  Sample Use Case

   This section does not aim to provide an exhaustive list of deployment
   scenarios where the use of the RADIUS CONVERT-IPv6 and CONVERT-IPv4
   attributes can be helpful.  Typical deployment scenarios are
   described, for instance, in [RFC6911].

   Figure 2 shows an example where a CPE is assigned a Converter.  This
   example assumes that the Network Access Server (NAS) embeds both
   RADIUS client and DHCPv6 server capabilities.









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         CPE                             NAS                      AAA
     DHCPv6 client                    DHCPv6 server              server
          |                                |                        |
          |---------DHCPv6 Solicit-------->|                        |
          |                                |----Access-Request ---->|
          |                                |                        |
          |                                |<----Access-Accept------|
          |                                |    CONVERT-IPv6        |
          |<-------DHCPv6 Advertisement----|                        |
          |        (OPTION_V6_CONVERT)     |                        |
          |                                |                        |
          |---------DHCPv6 Request-------->|                        |
          |                                |                        |
          |<---------DHCPv6 Reply----------|                        |
          |       (OPTION_V6_CONVERT)      |                        |

                       DHCPv6                          RADIUS

                     Figure 2: Sample Flow Example (1)

   Upon receipt of the DHCPv6 Solicit message from a CPE, the NAS sends
   a RADIUS Access-Request message to the AAA server.  Once the AAA
   server receives the request, it replies with an Access-Accept message
   (possibly after having sent a RADIUS Access-Challenge message and
   assuming the CPE is entitled to connect to the network) that carries
   a list of parameters to be used for this session, and which include
   Converter reachability information (namely a list of IP addresses).

   The content of the CONVERT-IPv6 attribute is then used by the NAS to
   complete the DHCPv6 procedure that the CPE initiated to retrieve
   information about the Converter it has been assigned.

   Upon change of the Converter assigned to a CPE, the RADIUS server
   sends a RADIUS CoA message [RFC5176] that carries the RADIUS CONVERT-
   IPv6 attribute to the NAS.  Once that message is accepted by the NAS,
   it replies with a RADIUS CoA ACK message.  The NAS replaces the old
   Converter with the new one.

   Figure 3 shows another example where a CPE is assigned a Converter,
   but the CPE uses DHCPv6 to retrieve a list of IP addresses of a
   Converter.










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        CPE                               NAS                      AAA
    DHCPv4 client                      DHCPv4 server              server
         |                                  |                        |
         |-----------DHCPDISCOVER---------->|                        |
         |                                  |----Access-Request ---->|
         |                                  |                        |
         |                                  |<----Access-Accept------|
         |                                  |    CONVERT-IPv4        |
         |<------------DHCPOFFER------------|                        |
         |         (OPTION_V4_CONVERT)      |                        |
         |                                  |                        |
         |------------DHCPREQUEST---------->|                        |
         |         (OPTION_V4_CONVERT)      |                        |
         |                                  |                        |
         |<-----------DHCPACK---------------|                        |
         |        (OPTION_V4_CONVERT)       |                        |

                       DHCPv4                         RADIUS

                     Figure 3: Sample Flow Example (2)

   Some deployments may rely on the mechanisms defined in [RFC4014] or
   [RFC7037], which allows a NAS to pass attributes obtained from a
   RADIUS server to a DHCP server.

5.  Security Considerations

   RADIUS-related security considerations are discussed in [RFC2865].

   Generic Convert security considerations are discussed in
   [I-D.ietf-tcpm-converters].

   MPTCP-related security considerations are discussed in [RFC6824] and
   [RFC6181].

   Traffic theft is a risk if an illegitimate Converter is inserted in
   the path.  Indeed, inserting an illegitimate Converter in the
   forwarding path allows to intercept traffic and can therefore provide
   access to sensitive data issued by or destined to a host.  To
   mitigate this threat, secure means to discover a Converter should be
   enabled.

6.  Table of Attributes

   The following table provides a guide as what type of RADIUS packets
   that may contain these attributes, and in what quantity.





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   Access- Access- Access-  Challenge Acct. # Attribute
   Request Accept  Reject             Request
    0+      0+      0        0         0+      TBA1 CONVERT-IPv4
    0+      0+      0        0         0+      TBA2 CONVERT-IPv6

   CoA-Request CoA-ACK CoA-NACK #   Attribute
     0+          0       0      TBA1 CONVERT-IPv4
     0+          0       0      TBA2 CONVERT-IPv6

   The following table defines the meaning of the above table entries:

   0  This attribute MUST NOT be present in packet.
   0+ Zero or more instances of this attribute MAY be present in packet.

7.  IANA Considerations

   IANA is requested to assign two new RADIUS attribute types from the
   IANA registry "Radius Attribute Types" located at
   http://www.iana.org/assignments/radius-types:

      CONVERT-IPv4 (TBA1)

      CONVERT-IPv6 (TBA2)

8.  Acknowledgements

   Thanks to Alan DeKok for the comments.

9.  References

9.1.  Normative References

   [I-D.ietf-tcpm-converters]
              Bonaventure, O., Boucadair, M., Gundavelli, S., Seo, S.,
              and B. Hesmans, "0-RTT TCP Convert Protocol", draft-ietf-
              tcpm-converters-12 (work in progress), October 2019.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2865]  Rigney, C., Willens, S., Rubens, A., and W. Simpson,
              "Remote Authentication Dial In User Service (RADIUS)",
              RFC 2865, DOI 10.17487/RFC2865, June 2000,
              <https://www.rfc-editor.org/info/rfc2865>.





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   [RFC6158]  DeKok, A., Ed. and G. Weber, "RADIUS Design Guidelines",
              BCP 158, RFC 6158, DOI 10.17487/RFC6158, March 2011,
              <https://www.rfc-editor.org/info/rfc6158>.

   [RFC6890]  Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
              "Special-Purpose IP Address Registries", BCP 153,
              RFC 6890, DOI 10.17487/RFC6890, April 2013,
              <https://www.rfc-editor.org/info/rfc6890>.

   [RFC8044]  DeKok, A., "Data Types in RADIUS", RFC 8044,
              DOI 10.17487/RFC8044, January 2017,
              <https://www.rfc-editor.org/info/rfc8044>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

9.2.  Informative References

   [I-D.nam-mptcp-deployment-considerations]
              Boucadair, M., Jacquenet, C., Bonaventure, O., Henderickx,
              W., and R. Skog, "Network-Assisted MPTCP: Use Cases,
              Deployment Scenarios and Operational Considerations",
              draft-nam-mptcp-deployment-considerations-01 (work in
              progress), December 2016.

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, DOI 10.17487/RFC2131, March 1997,
              <https://www.rfc-editor.org/info/rfc2131>.

   [RFC4014]  Droms, R. and J. Schnizlein, "Remote Authentication Dial-
              In User Service (RADIUS) Attributes Suboption for the
              Dynamic Host Configuration Protocol (DHCP) Relay Agent
              Information Option", RFC 4014, DOI 10.17487/RFC4014,
              February 2005, <https://www.rfc-editor.org/info/rfc4014>.

   [RFC4908]  Nagami, K., Uda, S., Ogashiwa, N., Esaki, H., Wakikawa,
              R., and H. Ohnishi, "Multi-homing for small scale fixed
              network Using Mobile IP and NEMO", RFC 4908,
              DOI 10.17487/RFC4908, June 2007,
              <https://www.rfc-editor.org/info/rfc4908>.

   [RFC5176]  Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
              Aboba, "Dynamic Authorization Extensions to Remote
              Authentication Dial In User Service (RADIUS)", RFC 5176,
              DOI 10.17487/RFC5176, January 2008,
              <https://www.rfc-editor.org/info/rfc5176>.




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   [RFC6181]  Bagnulo, M., "Threat Analysis for TCP Extensions for
              Multipath Operation with Multiple Addresses", RFC 6181,
              DOI 10.17487/RFC6181, March 2011,
              <https://www.rfc-editor.org/info/rfc6181>.

   [RFC6824]  Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
              "TCP Extensions for Multipath Operation with Multiple
              Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,
              <https://www.rfc-editor.org/info/rfc6824>.

   [RFC6911]  Dec, W., Ed., Sarikaya, B., Zorn, G., Ed., Miles, D., and
              B. Lourdelet, "RADIUS Attributes for IPv6 Access
              Networks", RFC 6911, DOI 10.17487/RFC6911, April 2013,
              <https://www.rfc-editor.org/info/rfc6911>.

   [RFC7037]  Yeh, L. and M. Boucadair, "RADIUS Option for the DHCPv6
              Relay Agent", RFC 7037, DOI 10.17487/RFC7037, October
              2013, <https://www.rfc-editor.org/info/rfc7037>.

   [RFC8415]  Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
              Richardson, M., Jiang, S., Lemon, T., and T. Winters,
              "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
              RFC 8415, DOI 10.17487/RFC8415, November 2018,
              <https://www.rfc-editor.org/info/rfc8415>.

Authors' Addresses

   Mohamed Boucadair
   Orange
   Rennes  35000
   France

   Email: mohamed.boucadair@orange.com


   Christian Jacquenet
   Orange
   Rennes
   France

   Email: christian.jacquenet@orange.com










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